Scientists have discovered a planet that appears to be similar to Earth circling the star closest to the sun, potentially a major step in the quest to find out if life exists elsewhere in the universe, research published on Wednesday showed. The relative proximity of the planet, known as Proxima b, gives scientists a better chance to eventually capture an image of it, to help them establish whether it has an atmosphere and water, which is believed to be necessary for life. Future studies may reveal if any atmosphere contains tell-tale chemicals of biological life, such as methane, according to a paper published in this week's issue of the journal Nature.
Explosions and gunfire rocked the American University of Afghanistan in Kabul on Wednesday, prompting desperate students trapped inside classrooms to plead for help, in the latest militant attack in the Afghan capital. No group has so far claimed responsibility for the assault, which comes just weeks after two university professors -- an American and an Australian -- were kidnapped at gunpoint near the school. Among them was Associated Press photojournalist Massoud Hossaini.